Omar Hamaha is a one-man whirlwind of piety and fury. For more than a decade he has been accused of raiding government outposts in Mauritania, Algeria and Niger; he has allegedly held Western hostages for extravagant ransoms, and — without any doubt — preached a ferocious asceticism through the barrel of a gun as he proselytized across the region. Riding with al-Qaeda in the Islamic Maghreb (AQIM), he crisscrossed the shadowless Sahara in the service of a god he envisioned as unforgiving as the desert itself. He invoked Koranic verses to protect himself from the “evil work of devils” and “the biting of snakes and scorpions,” learned to navigate by the sun, moon and stars, and believed that meteor showers were battles between jinnis and angels. It has been a ferocious transformation for a former student of accounting.

Since April, Hamaha, a man with a flaming red tuft of a beard and an oratorical style to match, has emerged as one of the most visible figures of the Islamist takeover of Mali’s ethnic Tuareg rebellion — even though he is an ethnic Arab. Clad in a camouflage smock and turban and clutching his Kalashnikov, he has become a familiar sight on the streets of Timbuktu. Residents say he mixes his fiery sermons with small acts of kindness — and poses for photos. He is implacably bound to a 21st century reimagining of 7th century Islam. “We are fighting in the name of religion,” he tells TIME by phone from Timbuktu, in one of several conversations over recent weeks that paint a rare portrait of the jihadist. “You know,” he says, “our struggle has just begun.”

He has championed the demolition of several Muslim mausoleums that UNESCO had declared historic. He said the destruction was justified on the grounds that “those who believe” in the veneration of such shrines “are driven by Satan.” On Tuesday, the Islamists in Timbuktu reportedly destroyed two more tombs at the 14th century Djingareyber mosque. “It’s forbidden by Islam to pray on tombs and ask for blessings,” says Hamaha, “Ansar Eddine is showing the rest of world, especially Western countries, that whether they want it or not, we will not let the younger generation believe in shrines as God, regardless of what the U.N., UNESCO, International Criminal Court or ECOWAS [the Economic Community of West African States] have to say. We do not recognize these organizations. The only thing we recognize is the court of God, Shari‘a. Shari‘a is a divine obligation, people don’t get to choose whether they like it or not.”

Officially, Hamaha, who is in his late 40s, is the military chief of Ansar Eddine, the predominantly Tuareg, Salafist outfit that emerged from the slipstream of a secular Tuareg rebellion before quickly supplanting it. But he has become the loudest proponent of jihad. “Our war is a holy war, not one of frontiers and limits,” he thundered in one video posted on YouTube earlier this year. “We are the mujahedin. Holy war!”

His zealotry might have remained a relatively obscure part of the Saharan underworld had Mali’s Tuareg rebellion and the subsequent military coup in Bamako, the Malian capital, not devoured the country this spring. The sudden tumult opened the door for al-Qaeda, which, in league with allies like Ansar Eddine, seized several major towns.

Hamaha occupies an unusual position in Africa’s jihadist firmament. He first fell under the spell of Islamist teachers in the mid-1980s in Algeria — a connection that years later would help propel him to a privileged position in AQIM, the local franchise of the terrorist movement. By 2008 he was one of the few Malians trusted by Mokhtar Belmokhtar, a powerful Algerian emir known for his Scarlet Pimpernel–like ability to avoid capture, and who for the most part surrounded himself with fellow nationals. Yet as northern Mali fell apart this spring, and Ansar Eddine muscled aside the secular Tuareg rebels of the Mouvement National pour la Liberation de l’Azawad (MNLA), Hamaha suddenly emerged as a key player among the jihadists of Ansar Eddine. He isn’t the only one. “Omar Hamaha and [Ansar Eddine spokesman] Sanda Ould Bouamama were certainly long-standing AQIM figures before the rebellion,” explains Andrew Lebovich, an analyst with the Navanti Group who focuses on Sahelian issues. “And I’m sure that there are others who fit that mold as well.”

Hamaha’s sudden shift in professional identity speaks to the complex tapestry of interests and tensions prevailing in northern Mali, and helps explain how al-Qaeda has exploited the chaos to such effect. To the extent that anyone can control a swath of desert bigger than France, Ansar Eddine, led by a veteran Tuareg troublemaker called Iyad Ag Ghali, is nominally in charge. But the specter of ethnic war weighs heavily over the region, where a previous Tuareg uprising between 1990 and ’96 led to interethnic atrocities. In Timbuktu, where Tuaregs are a minority, putting a local boy — like Hamaha, who hails from the city’s prominent Arab community — in charge makes better sense. Such expedients have allowed AQIM to inject operatives into competing jihadi outfits.

The intermingling makes it hard to tell how extensive al-Qaeda’s gains have been, but in all likelihood there’s more to them than meets the eye. “We have no good sense of how many militants there are, and even in the case of Ansar Eddine, it’s hard to tell how many of them are true Ansar personnel, vs. AQIM fighters or other militants who recently joined the organization,” says Lebovich. “The standard belief is that [Iyad Ag Ghali] has ultimate control over Ansar Eddine, and much of the writing on northern Mali has treated Iyad as the ‘master’ of the region. Personally, I think the situation is more complicated than that.”

Indeed, concern that northern Mali is rapidly becoming al-Qaeda’s most successful effort at establishing a caliphate to date has regional players scrambling for a response. Nigeria, Niger and Senegal have pledged to provide the core of a 3,270-member peacekeeping force to stabilize Mali’s politically fraught south and then tackle the militants. The announcement was promptly met with threats of retaliatory terrorist attacks. Even if such a campaign isn’t the jihadists’ priority, a suicide bombing deep inside Algeria by an AQIM ally called the Movement for Unity and Jihad in West Africa on June 29 showed that it is certainly within their means.

And the fact is any military intervention would be hard-pressed to defeat the jihadists, who are highly motivated, flush with weaponry looted from the arsenal of the fallen regime of Muammar Gaddafi in Libya and have an intimate knowledge of the terrain. Hamaha claims that the jihadists also have a powerful card up their sleeves — surface-to-air missiles seized in Tripoli last year. “We have Russia-made SAM 7A and SAM 7B [missiles] and U.S.-made stingers,” he boasts. “We made more than 20 trips … between Libya, Niger and Mali [last year] with at least 17 vehicles carrying weapons coming from Libya … Western countries are not going to take military action against us in northern Mali, because they know we have the missiles to shoot down airplanes, and it is complicated to deploy troops in the desert. It’s why they say the Malian crisis should be resolved though dialogue.” Although thousands of shoulder-launched missiles disappeared from Gaddafi’s armories, there have been no confirmed sightings of them in northern Mali to date, and Hamaha refused to furnish TIME with pictures of the missiles or their serial numbers. His point about the impregnability of the jihadists’ position, however, rings, for the immediate term at any rate, eerily true.